Description

Japanese beetles belong to the family Scarabaeidae, subfamily Rutelinae. Adults are broadly oval, 8 to 11 mm in length, metallic green, with coppery brown elytra that do not quite cover the end of the abdomen (Fig. 1A). The abdomen bears five patches of white hairs on either side, and another pair near its tip. Females, which tend to be slightly larger than males, have an elongate, spatula-shaped spur on the foretibia, used for digging. This spur is shorter and pointed in males.

Larvae are typical scarabaeiform grubs: C-shaped, grayish to cream colored, with three pairs of jointed legs, a distinct yellow-brown head capsule, and chewing mouthparts (Fig. 1B). Neonate grubs are about 1.5 mm in length, whereas the length of full-sized third instars is about 32 mm. The underside of the last abdominal segment, just anterior to the anal slit, bears two short rows of hairs forming a tiny, truncated V. This pattern distinguishes Japanese beetle larvae from the larvae of other common scarabs. The end of the abdomen appears dark because of ingested soil and food.